Individualized social niches in animals: Theoretical clarifications and processes of niche change.

What are social niches, and how do they arise and change? Our first goal in the present article is to clarify the concept of an individualized social niche and to distinguish it from related concepts, such as a social environment and a social role. We argue that focal individuals are integral parts of individualized social niches and that social interactions with conspecifics are further core elements of social niches. Our second goal in the present article is to characterize three types of processes-social niche construction, conformance, and choice (social NC3 processes)-that explain how individualized social niches originate and change. Our approach brings together studies of behavior, ecology, and evolution and integrates social niches into the broader concept of an individualized ecological niche. We show how clarifying the concept of a social niche and recognizing the differences between the three social NC3 processes enhance and stimulate empirical research.

Social niche shapes social behavior and cortisol concentrations during adolescence in female guinea pigs.

Individualized social niches arise in social groups, resulting in divergent social behavior profiles among group members. During sensitive life phases, the individualized social niche can profoundly impact the development of social behavior and associated phenotypes such as hormone (e.g. cortisol) concentrations. Focusing on adolescence, we investigated the relationship between the individualized social niche, social behavior, and cortisol concentrations (baseline and responsiveness) in female guinea pigs. Females were pair-housed in early adolescence (initial social pair formation), and a social niche transition was induced after six weeks by replacing the partner with either a larger or smaller female. Regarding social behavior, dominance status was associated with aggression in both the initial social pairs and after the social niche transition, and the results suggest that aggression was rapidly and completely reshaped after the social niche transition. Meanwhile, submissive behavior was rapidly reshaped after the social niche transition, but this was incomplete. The dominance status attained in the initial social pair affected the extent of submissive behavior after the social niche transition, and this effect was still detected three weeks after the social niche transition. Regarding cortisol concentrations, higher baseline cortisol concentrations were measured in dominant females in the initial social pairs. After the social niche transition, cortisol responsiveness significantly increased for the females paired with a larger, older female relative to those paired with a smaller, younger female. These findings demonstrate that the social niche during adolescence plays a significant role in shaping behavior and hormone concentrations in females.

Counter-strategies to infanticide: The importance of cubs in determining lion habitat selection and social interactions.

Animal social and spatial behaviours are inextricably linked. Animal movements are driven by environmental factors and social interactions. Habitat structure and changing patterns of animal space use can also shape social interactions. Animals adjust their social and spatial behaviours to reduce the risk of offspring mortality. In territorial infanticidal species, two strategies are possible for males: they can stay close to offspring to protect them against rivals (infant-defence hypothesis) or patrol the territory more intensively to prevent rival intrusions (territorial-defence hypothesis). Here, we tested these hypotheses in African lions (Panthera leo) by investigating how males and females adjust their social and spatial behaviours in the presence of offspring. We combined datasets on the demography and movement of lions, collected between 2002 and 2016 in Hwange National Park (Zimbabwe), to document the presence of cubs (field observations) and the simultaneous movements of groupmates and competitors (GPS tracking). We showed a spatial response of lions to the presence of offspring, with females with cubs less likely to select areas close to waterholes or in the periphery of the territory than females without cubs. In contrast, these areas were more selected by males when there were cubs in the pride. We also found social responses. Males spent more time with females as habitat openness increased but the presence of cubs in the pride did not influence the average likelihood of observing males with females. Furthermore, rival males relocated further after an encounter with pride males when cubs were present in the prides, suggesting that the presence of cubs leads to a more vigorous repulsion of competitors. Males with cubs in their pride were more likely to interact with male competitors on the edge of the pride's home range and far from the waterholes, suggesting that they are particularly assiduous in detecting and repelling rival males during these periods. In general, the strategies to avoid infanticide exhibited by male lions supported the territorial-defence hypothesis. Our study contributes to answer the recent call for a behavioural ecology at the spatial-social interface.

Does Social Support Play a Role in the Expression and Everyday Functioning Impact of Apathy in HIV Disease?

Clinically notable apathy occurs in approximately one-third of persons living with HIV (PLWH). Drawing from psychological theory, this cross-sectional study examined the interplay between apathy and social support in persons with (n = 143) and without (n = 61) HIV disease. Analyses were conducted using multiple regression and mediation procedures with 95th percentile bootstrap confidence intervals. Positive HIV serostatus and lower social support were associated with more frequent apathy, independent of other mood symptoms. Social support did not moderate apathy's associations with everyday functioning among PLWH, but post hoc analyses revealed that apathy mediated the relationship between social support and everyday functioning among PLWH. Stronger social support may provide a buffer against the frequency of apathy symptoms in persons with and without HIV disease. The relationship between lower social support and poorer everyday functioning in HIV might be partly explained by apathy. Longitudinal research is needed to examine the mechanisms of these relationships.

RESUMEN: La apatía clínicamente notable se produce en aproximadamente un tercio de las personas que viven con el VIH (PVVS). A partir de la teoría psicológica, este estudio transversal examinó la interacción entre la apatía y el apoyo social en personas con (n = 143) y sin (n = 61) enfermedad de VIH. Los análisis se llevaron utilizando procedimientos de regresión múltiple y mediación con intervalos de confianza bootstrap del 95º percentil. El estado serológico positivo respecto al VIH y un menor apoyo social se asociaron con una apatía más frecuente, independientemente de otros síntomas del estado de ánimo. El apoyo social no moderó las asociaciones de la apatía con el funcionamiento cotidiano entre las PVVS, pero los análisis post hoc revelaron que la apatía mediaba la relación entre el apoyo social y el funcionamiento cotidiano entre las PVVS. Un apoyo social más fuerte puede atenuar la frecuencia de los síntomas de apatía en personas con y sin VIH. La relación entre un menor apoyo social y un peor funcionamiento cotidiano en personas con VIH podría explicarse en parte por la apatía. Se necesitan investigaciones longitudinales para examinar los mecanismos de estas relaciones.

Is it legitimate to use unplanned hospitalizations as a quality indicator for cancer patients? A retrospective French cohort study with special attention to the influence of social deprivation.

PURPOSE: Readmission indicators are used around the world to assess the quality of hospital care. We aimed to assess the relevance of this type of indicator in oncology, especially for socially deprived patients. Our objectives were (1) to assess the proportion of unplanned hospitalizations (UHs) in cancer patients, (2) to assess the proportion of UHs that were avoidable, i.e., related to poor care quality, and (3) to analyze cancer patients the effect of patients' deprivation level on the type of UH (avoidable UHs vs. unavoidable UHs). METHODS: In a French university hospital, we selected all hospitalizations over a year for a random sample of cancer patients. Based on medical records, we identified those among UHs due to avoidable health problems. We assessed the association between social deprivation, home-to-hospital distance, or home-to-general practitioner with the type of UH (avoidable vs. unavoidable) via a multivariate binary logit estimation. RESULTS: Among 2349 hospitalizations (355 patients), there were 383 UHs (16 %), among which 38% were avoidable. Among UHs, the European Deprivation Index was significantly associated with the risk of avoidable UHs, with a lower risk of avoidable UH for patients with medium or high social deprivation. CONCLUSION: Our results suggest that the use of UHs rate as a quality indicator is questionable in oncology. Indeed, the majority of UHs were not avoidable. Furthermore, within UHs, those involving patients with medium or high social deprivation are more often unavoidable in comparison with other patients.

What influences life expectancy in people with dementia? Social support as an emerging protective factor.

BACKGROUND: The aim of this study was to investigate the role of support from the social environment for the life expectancy in people with dementia beyond well-established individual demographic and clinical predictors over a period of up to 8 years. METHODS: The analyses are based on data from 500 community-dwelling individuals in Germany who tested positive for dementia and were followed up for up to 8 years. Life expectancy was examined in relation to perceived social support as well as well-established socio-demographic (age, sex) and clinical predictors (cognitive status, functional status, comorbidities), using Cox regressions. RESULTS: Greater support from the social environment reduced the risk of mortality (hazard ratio [HR]: 0.78; 95% confidence interval [CI]: 0.63-0.98), with the role of emotional support being particularly important. Furthermore, higher age was associated with an increased mortality risk (HR: 1.08; 95% CI: 1.05-1.11), while female sex (HR: 0.64; 95% CI: 0.48-0.85) and higher cognitive (HR: 0.96; 95% CI: 0.93-0.98) and functional status (HR: 0.91; 95% CI: 0.86-0.97) were associated with higher life expectancy. CONCLUSION: Our study provides novel evidence that less support from the social environment, especially emotional support, is a risk factor for shorter life expectancy in people with dementia-beyond known clinical factors. Not only the clinical and caregiving needs but also their psychosocial needs of individuals with dementia should be emphasised.

Social setting interacts with hyper dopamine to boost the stimulant effect of ethanol.

Alcohol consumption occurring in a social or solitary setting often yields different behavioural responses in human subjects. For example, social drinking is associated with positive effects while solitary drinking is linked to negative effects. However, the neurobiological mechanism by which the social environment during alcohol intake impacts on behavioural responses remains poorly understood. We investigated whether distinct social environments affect behavioural responses to ethanol and the role of the dopamine system in this phenomenon in the fruit fly Drosophila melanogaster. The wild-type Canton-S (CS) flies showed higher locomotor response when exposed to ethanol in a group setting than a solitary setting, and there was no difference in females and males. Dopamine signalling is crucial for the locomotor stimulating effect of ethanol. When subjected to ethanol exposure alone, the dopamine transport mutant flies fumin (fmn) with hyper dopamine displayed the locomotor response similar to CS. When subjected to ethanol in a group setting, however, the fmn's response to the locomotor stimulating effect was substantially augmented compared with CS, indicating synergistic interaction of dopamine signalling and social setting. To identify the dopamine signalling pathway important for the social effect, we examined the flies defective in individual dopamine receptors and found that the D1 receptor dDA1/Dop1R1 is the major receptor mediating the social effect. Taken together, this study underscores the influence of social context on the neural and behavioural responses to ethanol.

Early-life group size influences response inhibition, but not the learning of it, in Japanese quails.

In complex social environments, animals benefit from suppressing inappropriate responses (known as Response Inhibition) to avoid conflicts and maintain group cohesion. Recent research suggests that an individual's early-life social environment can shape their response inhibition. However, these findings have mostly been correlational, and results vary across species. Furthermore, the role of learning is often overlooked when measuring response inhibition, despite its potential importance to understanding group differences. We investigated the effect of early-life group size, a key determinant of social complexity, on response inhibition in Japanese quails (Coturnix japonica), whilst taking the role of learning into account. Quails (n = 120) were raised in either small groups of five or large groups of 15 individuals. Response inhibition was assessed using the cylinder task. Up to ten trials were administered to assess whether the birds' responses changed with increasing experience of the task. Among the quails that completed ten trials, we found that those raised in large groups consistently spent less time pecking the cylinder than those raised in small groups. The quails' responses were also influenced by their body condition, food motivation and sex. Importantly, the quails learned to inhibit their responses - successful trials increased, and time spent pecking the cylinder decreased, across ten trials. However, learning rates did not differ between the treatment groups. These findings suggest that early-life social group size promotes the development of response inhibition in quails, but not their learning of it, during the cylinder task.

Predicting adolescents' continuation in club sports: A prospective cohort study of the importance of personal and contextual motivational factors in five sports in Denmark.

PURPOSE: The purpose of this prospective cohort study was to investigate the influence of types of motivation, basic psychological needs satisfaction and of a coach-created motivational climate on continued participation in youth sports across types of sport, competitive levels, ages, and gender. METHODS: Participants were 7110 adolescent (age 12-20 years) members of leisure time club organized in basketball, handball, football, badminton, and gymnastics in Denmark. Motivational regulation was measured with BRSQ-6, basic psychological needs satisfaction and frustration were measured with PNSS-S, and coach-created climate was measured with the EDMCQ-C. The participants' continuation or dropout was measured at the beginning of the following season with a short electronic questionnaire. RESULTS: Intrinsic motivation, identified behavior regulation, experiences of competence, relatedness, and autonomy, as well as a coach-created empowering motivational climate, were associated with continuation both in the sport and in the club the following season across different sports, genders, age groups, and competitive levels. Introjected and external behavior regulation, frustrations with the need to experience competence, relatedness, and autonomy, as well as a disempowering coach-created climate, were associated with dropout. CONCLUSION: In Danish youth sports, autonomous motivation, satisfaction of basic psychological needs, and an empowering coach-created motivational climate have a positive impact on the continuation of the sport and the club the following season. In contrast, controlled types of motivation, needs frustration, and a disempowering coach-created climate are associated with dropout. This is the case at both elite and recreational levels, for boys and girls, adolescents, and youth.

The interplay between social environment and opportunities for physical activity within the built environment: a scoping review.

BACKGROUND: The association between social and built environments plays a crucial role in influencing physical activity levels. However, a thorough understanding of their combined impact remains unclear. This scoping review seeks to clarify the interplay between social environments and opportunities for physical activity within different built environments, with a particular focus on the implications of socioeconomic status and urban planning on physical activity participation. METHODS: We conducted a systematic literature search across several databases to identify studies exploring the associations between social factors, built environment characteristics, and physical activity levels. The inclusion criteria were studies published in English between 2000 and 2022, encompassing urban, suburban, and rural contexts. Thematic analysis was employed to categorise studies based on the specific aspects of the built environment they investigated (walking infrastructure, cycling infrastructure, parks and open spaces, and sports facilities) and the social determinants they examined. RESULTS: A total of 72 studies were included in the review, illustrating a multifaceted relationship between access to physical activity opportunities and social determinants such as socioeconomic status, community engagement, and urban design. The findings highlight the significant role of socioeconomic factors and the quality of PA infrastructure in promoting or hindering PA across communities. Effective urban planning was identified as crucial in providing expanded physical activity opportunities, notably through more pedestrian-friendly environments, comprehensive cycling infrastructure, and accessible green spaces and sports facilities. CONCLUSIONS: This review emphasises the significant impact of socioeconomic status and urban planning on access to physical activity opportunities. This underscores the necessity for urban planning policies to adopt an inclusive approach, considering the varied needs of different population groups to ensure equitable access to physical activity resources. Such strategies are crucial for public health initiatives aimed at enhancing physical activity levels across diverse community sectors, offering a potential avenue to alleviate health disparities associated with inactivity.

Correlation analysis of the urban community environment and health promotion among adults aged ≥ 55 years: the mediating role of physical activity.

BACKGROUND: Physical health (PH), including muscle strength, endurance, and the ability to perform daily physical tasks, gradually declines with increasing age, leading to disability and an increased disease burden. Both the urban community environment (UCE) and physical activity (PA) were linked to PH. METHODS: A total of 625 participants aged 55 years and older from Haidian and Chaoyang Districts in Beijing, China, were included in the study from September to December 2023.PH was assessed by a combined score of four tests, including BMI, chronic disease, depression and self-rated health.The Neighborhood Environment Walkability Scale-Abbreviated (NEWS-A), Center for Epidemiological Survey-Depression Scale (CES-D), Physical Activity Scale for Elderly (PASE) and Social Support Rate Score (SSRS) were collected. The analysis was carried out with SPSS v.20 and Amos 24, and the results were validated via structural equation modeling (SEM). RESULTS: The urban community environment was positively associated with the health level of older adults. Specifically, the standardized path coefficients indicate that the influence of the built environment (0.72-0.88) was greater than that of the social environment (0.43-0.55) and personal attributes (0.22-0.37) on older adults' health. Physical activity demonstrated both a mediating effect and an indirect effect, highlighting its significant value as a mediating variable. CONCLUSIONS: The urban community environment has a positive impact on promoting the physical health of older adults, with the influence of the built environment being greater than that of the social environment and personal attributes on their physical health. Physical activity acts as a mediator between the urban community environment and the physical health of older adults.

Determinants of food insecurity among adults residing in peri-urban municipal settings in Flanders, Belgium.

Food insecurity is a global public health issue associated with noncommunicable diseases. Individual factors are strongly associated with food insecurity, but there is limited literature on the broader impact of both the social and food environments on food insecurity in non-English speaking European countries, given that the research was predominantly conducted in Anglophone settings. In addition, these studies have mostly been conducted in urban areas. Therefore, this study aimed to identify the main determinants of food insecurity among adults living in peri-urban areas in Flanders, Belgium. Data on socio-demographics, neighborhood social cohesion, social isolation, and perceived food environments were collected from 567 adults through a self-administered questionnaire, and objective data on the food environment were obtained through (commercial) databases on food outlets. Food insecurity was measured using the USDA Household Food Security Survey Module. Multivariable logistic regression models revealed that lower socioeconomic status (OR14.11,95%CI:4.72;61.11), reasonable (OR4.16,95%CI: 2.11;8.47) to poor and very poor (OR6.54,95%CI: 2.11;8.47) subjective health status, and living in private (OR7.01, 95% CI:3.0;17.0) or government-assisted (OR6.32,95%CI: 3.13;13.26) rental housing significantly increased the odds of food insecurity. Additionally, residing in a neighborhood with low (OR2.64, 95% CI:1.13;6.26) to medium (OR2.45,95% CI:1.21;5.11) social cohesion, having a neutral opinion (OR4.12,95%CI:1.51;11.54) about the availability of fruit and vegetables in one's neighborhood, and having an opinion that fruit and vegetable prices are too expensive (OR5.43,95% CI 2.26;14.4) significantly increased the odds of experiencing food insecurity. This study underscores the need for policies that consider factors related to social and food environments, in addition to individual factors, to effectively address food insecurity.

1 km of living area: age differences in the association between neighborhood environment perception and self-rated health among Chinese people.

OBJECTIVES: This study aimed to explore the age differences in the relationship between neighborhood environment perception and self-rated health among Chinese people. STUDY DESIGN: This is cross-sectional study. METHODS: The participants were 2,631 residents aged 18 and above from 2021 Chinese General Social Survey (CGSS). Self-rated health was reported by residents. Neighborhood environment was measured by respondents' subjective perception of 1 km living area. Ordered logit regression models were used to examine the relationship between neighborhood environment perception and self-rated health. RESULTS: In summary, 42.08% were classified as young adults, and 57.92% were classified as middle-aged and older adults. Young adults with higher perception of neighborhood social environment were more likely to perceive good health. Neighborhood built environment was significantly associated with self-rated health among middle-aged and older adults. CONCLUSION: The neighborhood environment is an important predictor of the health of its residents. Neighborhood environmental modifications should be tailored to meet the needs of different age groups, promoting health equity.

Determinants of health status in older patients with transthyretin cardiac amyloidosis: a prospective cohort study.

BACKGROUND: Whether, and to what extent, frailty and other geriatric domains are linked to health status in patients with transthyretin cardiac amyloidosis (ATTR-CA) is unknown. AIMS: To determine the association of frailty with health status [defined by the Kansas City Cardiomyopathy Questionnaire (KCCQ)] in patients with ATTR-CA. METHODS: Consecutive ATTR-CA patients undergoing cardiovascular assessment at a tertiary care clinic from September 2021 to September 2023 were invited to participate. KCCQ, frailty and social environment were recorded. Frailty was assessed using the modified Frailty Index (mFI), mapping 11 variables from the Canadian Study of Health and Aging (frailty ≥0.36). RESULTS: Of 168 screened ATTR-CA patients, 138 [83% men, median age of 79 (75-84) years] were enrolled in the study. Median KCCQ was 66 (50-75). wtATTR-CA was the most prevalent form (N = 113, 81.9%). The most frequent cardiac variant was Ile68Leu (17/25 individuals with vATTR-CA). Twenty (14.5%) patients were considered frail, and prevalence of overt disability was 6.5%. At multivariable linear regression analysis, factors associated with worsening KCCQ were age at evaluation, the mFI, NYHA Class, and NAC Score. Gender, ATTR-CA type, phenotype, and LVEF were not associated with health status. DISCUSSION: In older patients diagnosed with ATTR-CA, frailty, symptoms, and disease severity were associated with KCCQ. CONCLUSIONS: Functional status is a determinant of quality of life and health status in older individuals with a main diagnosis of ATTR-CA. Future research may provide more in-depth knowledge on the association of frailty in patients with ATTR-CA with respect to quality of life and prognosis.

Effects of social environments on male primate HPG and HPA axis developmental programming.

Developmental plasticity is particularly important for humans and other primates because of our extended period of growth and maturation, during which our phenotypes adaptively respond to environmental cues. The hypothalamus-pituitary-gonadal (HPG) and hypothalamus-pituitary-adrenal (HPA) axes are likely to be principal targets of developmental "programming" given their roles in coordinating fitness-relevant aspects of the phenotype, including sexual development, adult reproductive and social strategies, and internal responses to the external environment. In social animals, including humans, the social environment is believed to be an important source of cues to which these axes may adaptively respond. The effects of early social environments on the HPA axis have been widely studied in humans, and to some extent, in other primates, but there are still major gaps in knowledge specifically relating to males. There has also been relatively little research examining the role that social environments play in developmental programming of the HPG axis or the HPA/HPG interface, and what does exist disproportionately focuses on females. These topics are likely understudied in males in part due to the difficulty of identifying developmental milestones in males relative to females and the general quiescence of the HPG axis prior to maturation. However, there are clear indicators that early life social environments matter for both sexes. In this review, we examine what is known about the impact of social environments on HPG and HPA axis programming during male development in humans and nonhuman primates, including the role that epigenetic mechanisms may play in this programming. We conclude by highlighting important next steps in this research area.

Assessing Physical Therapists' Outdoor Walking Recommendations and Neighborhood Walkability for Older Adults.

BACKGROUND/OBJECTIVES: Neighborhood walkability is the extent to which built and social environments support walking. Walkability influences older adults' participation in outdoor physical activity. Identifying factors that influence physical therapists' (PTs) decisions about prescribing outdoor walking is needed, especially for those who are aging in place. The purpose of this study is to describe the neighborhood walkability knowledge, perceptions, and assessment practices of PTs who work with community-dwelling older adults. METHODS: A cross-sectional survey was sent via email to 5,000 PTs nationwide. The 40-item survey assessed walking prescriptions, walkability perceptions and assessments, and gathered demographic data. Categorical variables were compared using Chi-square analyses. RESULTS: Using a total of 122 PTs who worked in outpatient geriatric physical therapy settings, a significant difference was found between perceptions of whether PTs should assess walkability and whether they actually assess walkability (χ2 = 78.7, p < .001). Decisions to prescribe outdoor walking were influenced by the availability (n = 79, 64.8%) and maintenance (n = 11, 9.0%) of sidewalks, crime (n = 9, 7.4%), terrain (n = 7, 5.7%), and aesthetics (n = 6, 4.9%). Objective walkability measures were not used by the respondents. CONCLUSION: When considering the assessment of walkability, PTs prioritize the built environment over the social environment. Although most believe it is the responsibility of the PT to assess walkability, most do not. Significance/Implications: Assessment of walkability may allow PTs to identify barriers and make more informed recommendations concerning outdoor walking for older adults. Objective measures are available for PTs when prescribing outdoor walking.

Health-Oriented Environmental Categories, Individual Health Environments, and the Concept of Environment in Public Health.

The term 'environment' is not uniformly defined in the public health sciences, which causes crucial inconsistencies in research, health policy, and practice. As we shall indicate, this is somewhat entangled with diverging pathogenic and salutogenic perspectives (research and policy priorities) concerning environmental health. We emphasise two distinct concepts of environment in use by the World Health Organisation. One significant way these concepts differ concerns whether the social environment is included. Divergence on this matter has profound consequences for the understanding of health and disease, for measures derived from that understanding targeting health promotion and disease prevention, and consequently, for epistemic structures and concept development in scientific practice. We hope to improve the given situation in public health by uncovering these differences and by developing a fruitful way of thinking about environment. Firstly, we side with the salutogenic conception of environment as a health resource (as well as a source of health risks). Secondly, we subdivide the concept of environment into four health-oriented environmental categories (viz., natural, built-material, socio-cultural, and psychosocial) and we link these with other theoretical notions proposed in the health sciences literature. Thirdly, we propose that in public health 'environment' should be understood as consisting of all extrinsic factors that influence or are influenced by the health, well-being, and development of an individual. Consequently, none of the four categories should be excluded from the concept of environment. We point out the practical relevance and fruitfulness of the conception of environment as a health source and frame this in causal terms, representing individual health environments as causal networks. Throughout, we side with the view that for the design of human health-promoting settings, increased attention and consideration of environmental resources of salutogenic potential is particularly pressing.

The effects of social environment on AD-related pathology in hAPP-J20 mice and tau-P301L mice.

In humans, social factors (e.g., loneliness) have been linked to the risk of developing Alzheimer's Disease (AD). To date, AD pathology is primarily characterized by amyloid-ß plaques and tau tangles. We aimed to assess the effect of single- and group-housing on AD-related pathology in a mouse model for amyloid pathology (J20, and WT controls) and a mouse model for tau pathology (P301L) with and without seeding of synthetic human tau fragments (K18). Female mice were either single housed (SH) or group housed (GH) from the age of 6-7 weeks onwards. In 12-week-old P301L mice, tau pathology was induced through seeding by injecting K18 into the dorsal hippocampus (P301LK18), while control mice received a PBS injection (P301LPBS). P301L mice were sacrificed at 4 months of age and J20 mice at 10 months of age. In all mice brain pathology was histologically assessed by examining microglia, the CA1 pyramidal cell layer and specific AD pathology: analysis of plaques in J20 mice and tau hyperphosphorylation in P301L mice. Contrary to our expectation, SH-J20 mice interestingly displayed fewer plaques in the hippocampus compared to GH-J20 mice. However, housing did not affect tau hyperphosphorylation at Ser202/Thr205 of P301L mice, nor neuronal cell death in the CA1 region in any of the mice. The number of microglia was increased by the J20 genotype, and their activation (based on cell body to cell size ratio) in the CA1 was affected by genotype and housing condition (interaction effect). Single housing of P301L mice was linked to the development of stereotypic behavior (i.e. somersaulting and circling behavior). In P301LK18 mice, an increased number of microglia were observed, among which were rod microglia. Taken together, our findings point to a significant effect of social housing conditions on amyloid plaques and microglia in J20 mice and on the development of stereotypic behavior in P301L mice, indicating that the social environment can modulate AD-related pathology.

Traveling Together: A Road Map for Researching Neighborhood Effects on Population Health and Health Inequities.

As evidence of the relationship between place and health mounts, more epidemiologists and clinical science researchers are becoming interested in incorporating place-based measures and analyses into their examination of population health and health inequities. Given the extensive literature on place and health, it can be challenging for researchers new to this area to develop neighborhood-effects research questions and apply the appropriate measures and methods. This paper provides a road map for guiding health researchers through the conceptual and methodological stages of incorporating various dimensions of place into their quantitative health research. Synthesizing across reviews, commentaries, and empirical investigations, the road map consists of 4 broad stages for considering place and health: 1) why?: articulating the motivation for assessing place and health and grounding the motivation in theory; 2) what?: identifying the relevant place-based characteristics and specifying their link to health to build a conceptual framework; 3) how?: determining how to operationalize the conceptual framework by defining, measuring, and assessing place-based characteristics and quantifying their effect on health; and 4) now what?: discussing the implications of neighborhood research findings for future research, policy, and practice. This road map supports efforts to develop conceptually and analytically rigorous neighborhood research projects.

Exposure, Susceptibility, and Recovery: A Framework for Examining the Intersection of the Social and Physical Environments and Infectious Disease Risk.

Despite well-documented evidence that structurally disadvantaged populations are disproportionately affected by infectious diseases, our understanding of the pathways that connect structural disadvantage to the burden of infectious diseases is limited. We propose a conceptual framework to facilitate more rigorous examination and testing of hypothesized mechanisms through which social and environmental factors shape the burden of infectious diseases and lead to persistent inequities. Drawing upon the principles laid out by Link and Phelan in their landmark paper on social conditions (J Health Soc Behav. 1995;(spec no.):80-94), we offer an explication of potential pathways through which structural disadvantage (e.g., racism, sexism, and economic deprivation) operates to produce infectious disease inequities. Specifically, we describe how the social environment affects an individual's risk of infectious disease by 1) increasing exposure to infectious pathogens and 2) increasing susceptibility to infection. This framework will facilitate both the systematic examination of the ways in which structural disadvantage shapes the burden of infectious disease and the design of interventions that can disrupt these pathways.